An agricultural harvester known as a “combine” is historically termed such because it combines multiple harvesting functions with a single harvesting unit, such as picking, threshing, separating and cleaning. A combine includes a header which removes the crop from a field, and a feeder housing which transports the crop matter into a threshing rotor. The threshing rotor rotates within a perforated housing, which may be in the form of adjustable concaves and performs a threshing operation on the crop to remove the grain. Once the grain is threshed it falls through perforations in the concaves onto a grain pan. From the grain pan the grain is cleaned using a cleaning system, and is then transported to a grain tank onboard the combine. A cleaning fan blows air through the sieves to discharge chaff and other debris toward the rear of the combine. Non-grain crop material such as straw from the threshing section proceeds through a residue system, which may utilize a straw chopper to process the non-grain material and direct it out the rear of the combine. When the grain tank becomes full, the combine is positioned adjacent a vehicle into which the grain is to be unloaded, such as a semi-trailer, gravity box, straight truck, or the like; and an unloading system on the combine is actuated to transfer the grain into the vehicle.
During the process of harvesting in a combine, the desired grain is gathered and saved while crop material other than the desired grain is expelled from the combine. The non-grain crop material or crop residue is usually derived from two areas in the combine, the threshing rotor and the cleaning system. The material expelled from the threshing rotor is generally referred to as straw and includes much of the larger plant material such as stalks, stems, cobs leaves and the like as well as foreign or non-crop material. The material expelled from the cleaning system is generally referred to as chaff and includes much of the finer plant material residue, such as pods, husk fragments and particulates. The combined flows of crop residue to be expelled from the combine can be dealt with in several ways; however, the processes for redepositing the residue material back into the field can be categorized generally as either windrowing or spreading.
In a windrowing process, the crop residue is deposited onto the harvested crop stubble in a continuous narrow stream or windrow, which is much narrower than the harvested swath width. Accumulated in this manner, the windrowed residue material can be picked up easily for baling or other subsequent processing or use.
In a spreading process, a mechanical device distributes the straw and/or chaff evenly across the extent of the combine header cutting width. The material to be spread is usually chopped to a short length so that after spreading the material will break down quickly to add nutrients to the soil and/or to be sufficiently small so as to not interfere with subsequent tilling or seeding operations.
Residue spreaders can be of horizontal and vertical types. A horizontal spreader includes a spreader device with a rotor driven on a generally vertical axis and a plurality of vanes or paddles on the rotor to propel residue in a wide swath behind the combine. Commonly, two such side-by-side rotors are used, the rotors rotating in opposite directions within a housing. After being chopped, the crop residue enters the rotor area through a vertical inlet in the spreader housing, and as the paddles rotate about the axis the residue is propelled towards a tangential outlet of the housing. Typically, the tangential outlet of the housing is formed by a deflector whose orientation and shape determines the spread pattern of the crop residue. It is known to use adjustable structures of the housing and deflector to control the outlet flow of material, by adjusting the size and position of the deflector and of the space between the rotor paddles and the adjustable structures, to achieve a substantially even distribution of the crop residue material across the width of a distribution swath behind the combine. It is desirable to achieve an even distribution of material for more even and consistent residue material breakdown and to facilitate subsequent field tilling and seeding operations.
A vertical spreader includes a rotor driven about a generally horizontal axis and a plurality of vanes or paddles are on the rotor to propel residue from the spreader housing. Again, commonly two such side-by-side rotors are used, rotating in opposite directions.
As combine harvesters increase in size and crop processing capability, the width of the header of the combine can increase in order to make fewer passes in a field. As the width of the header increases, so too must the spread width of crop residue behind the combine in order to uniformly cover the field which now is mostly bare of crops. The spread width can be adjusted, for example, by increasing the rotational speed of the rotors and paddles so the crop material is spread a greater distance from the spreader system. The positioning of the deflector is controlled to prevent, for example, crop residue being spread onto standing crop, which would then be collected and reprocessed by the combine.
One particular problem that arises with greater spread widths is the creation of “stripes” of high and low volumes of crop residue along the driving direction of the combine in hard crop conditions. The stripes of high and low crop residue volumes are an uneven thickness of the crop residue, with higher thickness of the crop residue resulting in a high volume stripe and lower thickness of the crop residue resulting in a low volume stripe. The stripes of crop residue distribution can lead to some areas of the field being practically bare of crop residue, with little added nutrients from the residue, while other areas of the field have excess crop residue that can interfere with seeding and tilling.
What is needed in the art is a crop residue spreader that will uniformly distribute the crop residue across the full cut width of the combine.